Latest News at the ShadeTree

I do most of my riding over to USC Upstate and back and this time of year its pretty empty at the times I'm there. I just spotted some pretty good areas for riding the electric bikes that I've got in the works. The moonlander and the KX 85 conversion. I've got a huge motor coming for the dirt bike. It's a 12080 size KV 150 monster good for 72 volts. I've also located some ESC's that should be ideal for this motor... they are HV opto type rated for 300 amps at 20s. 20s is 84 volts.... I'll probably run 18s which will be about 75 volts.

Road Testing

I've been doing a lot of riding just to see how things hold up. I did have to make one mod to the secondary belt drive. I was having some issues with the belt jumping teeth on hard acceleration. I was considering going to an 8M HTD belt drive on the secondary but off the shelf pulley selection is not so good. Part of the problem is that the rear suspension makes it difficult to maintain proper belt tension. The simplest cure was to add a belt tensioner. This ended up being pretty easy to implement and made a huge improvement. No more belt slipping.

I'm geared for a top speed of about 28 MPH. I think this is about ideal overall. I'm current limiting to 30 amps which is about 1500 watts. I've been logging my watt hrs per mile. Pumping up the tires made a pretty significant improvement . Also been doing more and more pedaling along and this has a big impact as well.

The devil is in the details.

Finally getting around to some decent riding weather. I've been mainly doing some detailing to improve the ridability of the trike. Two things that I have done that made a huge improvement was adding more batteries, and implementation of current limiting in my speed controller.

 I added two battery boxes and mounted them under the seat. I used anderson connectors so that it would be easy to unplug each battery box and swap it out for another. I have a total of 8 batteries now wired for 20 amp hours at 44 volts. This should give a range of 25 - 30 miles. Moving the battery weight to under the seat made a pretty significant improvement in the handling as they are now the lowest thing on the trike.

With the help of input from some folks on the Endless-Sphere site I have implemented current limiting in my speed controller. It makes it much more ridable and can be set so that it encourages you to pedal along. It should also help improve the range on a battery charge. I have started documenting watts per mile so that I can actually see if I'm making improvements over time.

I've been working on adding a liquid crystal display so that I can monitor motor and battery info real time. I have had this working in different locations and I added wiring inside the frame to have the LCD where I could see it while riding. I'm not sure why at this point but so far attempts to use the speed controller with the new wiring have not been so good. It acts as though the throttle input is unstable when using the internal wiring. I also changed to the Arduino Micro in the process so I'm not sure which is the problem. Thats the only real unsolved issue at this point. Hopefully will get that worked out soon.

Offroad

I took the trike offroad for the first time... this is just before I started the electric conversion. It did better than I would have thought. I mainly added this because I don't have a picture of the whole trike on this blog. I've ordered some more batteries that should be here in a few days. If you know anything about Spartanburg, SC... this is near the USC Upstate campus. I do a lot of riding from where I live to there and back.

Reduction Drive Details

This has been a bit of a quick and dirty from the outset but evolved pretty quickly into what you see here. The first jackshaft is housed in a piece of 1 inch schedule 40 pipe which has a rough ID of just over .750 inch. I originally had bronze bearings in it but now have needle bearings with an ID of .500 inch and OD of .750 inch. The needle bearing are a tad over size to make for a press fit into a .750 inch hole. The ID of the tubing has a bit of a rough finish so the bearing have so far stayed in place in spite of being a relatively loose fit. I originally had no seals but have since added seals on each end to keep the lube in place.


If  I were to try to duplicate this on a KMX Typhoon (I hope too in the not to distant future) I think I will get some chrome moly tubing which would be both lighter and a better fit.... tho in practice it has not been an issue so far. If it becomes an issue (loose fit) I would probably just use locktight on the bearings to insure that they stay where intended.I machined a piece of aluminum to go into the BB for the second jackshaft. The hole in it is offset to allow for tensioning the belt. It is held in place in the BB by a set screw. It has the same needle bearings and seals as the other shaft though a much tighter fit. I'm using .500 inch hardened shafts both places.

All the pulleys and freewheel adapter are held in place by set screws onto flats ground in the hardened shafts. Not overly elegant but effective. The belts are both 450 mm length 15 mm wide and are the 5m htd tooth style.

Motor Drive Details

A few details about some of the parts I'm using. I've bought quite a few motors and drives from http://www.hobbypartz.com for use on tri copters, quad copters, and RC planes. I have been pleased with their performance and cost. They usually have free shipping on orders over $100 and occasionally have 10% off sales.

The motor is the Tacon Bigfoot 160.... it is a 63mm x 64 mm motor with 245 KV and rated about 2700 watts. It is the biggest motor they sell and normal price is about  $55. I bought three of them... two for trikes and 1 for a Yak 54 with a 72 inch wing span. I just ran it yesterday on the plane with a 16 x 8 prop and it was pulling a little over 50 amps on 44 volts for around 2100 watts at full power. A bigger prop would up the power but probably gonna try it with that prop. I'll try it again in a few days and measure the thrust. 

The drive is a 100 amp HV good for 12s LiPo and came with a couple of undocumented (on their webpage) addons. Four capacitors in parallel across the power input terminals. An interface that I think you can hook between two motor phases and gives you a low level output that could go to a tach or possibly a governor on helicopter applications. I'm not planning on using that. The drive is about $115 and so far is performing well. It does not have the battery eliminator circuit so power for my RBB servo tester is from a 7.4 volt battery. the RBB board has a 5 volt regulator on it.